Unsolved
This post is more than 5 years old
5 Posts
0
6395
Equallogic SAN and SQL - To use Virtualization Technology or Carve up the drives like Best Practices advise?
I am currently trying to research and get some perspective on deploying a Server 2003 Cluster (MSCS) and SQL 2000, Entry/Low End Equallogic SAN, 15 x 15k SAS Drives, Active/Passive iSCSI dual controllers.
Per Microsoft, the typical advice for deploying SQL on a SAN, is to dedicate Spindles for each function of SQL:
RAID 1 (1+1): Logs
RAID 1 (1+1): TempDB
RAID 5 or 10: SQL Data Disks
And in a typical deployment, I would carve those disks out accordingly, ensuring that each RAID Group/Pool was dedicated to perform data transactions on that SPECIFIC I/O Profile, alone.
In a Virtualization situation, I understand you create a simple RAID 10 Pool and put the associated Volumes on that Pool. I understand the function of the Virtualization technology and that it's supposed to balance and stripe the data across it's spindles to ensure an even distribution of data, for IOPS purposes, etc. But with the "hands off" benefits.. come the natural latency and overhead that a Virtualization pool provides.
But, what is the true stand on this technology, specifically with the lower-mid/entry Equallogic products from Dell? Being that we are working with Active/Passive iSCSI 1gbps link technology, is proceeding with the "hands off" Virtualization truly optimal in a case where you have a truly IOPS intensive application requiring extensive random & sequential read/writes against ALL disks, at the same time? Throw in the mix data dedupe or SQL to Disk/to Tape backups.... now you add more Sequential reads & writes on top of the Random SQL Data disk reads and Sequential SQL Log writes... It seems like if you have one Pool assigned to manage it all, unless you have a big Fast Cache/Large Controller Cache/Memory, you would inevitably run into severe bottlenecks.. the Spindles and heads can only do so much at a time.
Thoughts? I'm hoping a Dell engineer, or someone that has actually ran into this, might chime in.. I don't know if I can call Dell support and speak to anyone that would have any insight on something like this. I do truly appreciate any feedback or ideas for this... as we currently have someone deployed with the Virtualization model enabled, and there are some issues.. that I feel are related to my overall concern for the technology.
Thank you in advance!
--Brian
DELL-Joe S
7 Technologist
7 Technologist
•
729 Posts
0
December 20th, 2011 06:00
First, to clarify, only one RAID policy can be configured per EqualLogic array member, and a member can only be in one pool. You indicated that you were only interested in one array, so if you plan on using two different RAID policies, you would need two arrays (these can be in the same pool or different pools, based on several factors, i.e., such as load balancing requirements or utilizing the latest sub-volume tiering technology between members, etc.).
Also, the PS Array doesn’t support RAID 1, the supported policies are:
RAID 10 (with or without spares)
RAID 50 (with or without spares)
RAID 5
RAID 6 (with or without spares)
RAID 6 Accelerated (supported only on array models with disk drive configurations that include solid-state drives and hard disk drives.)
If you haven’t already seen these, I think a good place to start is:
en.community.dell.com/.../guides.aspx
In the list, review the following:
EqualLogic Configuration Guide
PS Series Best Practices Deploying Microsoft® Windows® Clustering with an iSCSI SAN
Deploying Pools and Tiered Storage in a PS Series SAN
PS Series Storage Arrays Choosing a member RAID Policy
PS Series Groups Deploying Microsoft SQL Server in an iSCSI SAN
Regarding performance, the newest base model of the EqualLogic PS Series Array is the PS4100, this has 4GB of cache memory per controller, and 2, 1GbE interfaces. The key to a high performance in a SAN, is the network that it is built on; i.e., quality NICs and/or HBAs; utilizing MPIO (multi-path IO) on the hosts; switches with enough buffers per port; and the Array disk speeds, number of spindles, and cache memory.
You may also want to contact one of our technical sales folks, who can talk to you and provide some guidance in sizing your SAN network based on your specific needs (you shouldn’t get too much sales BS from them… if you know what I mean)
Contact them here (look for the sales section): www.equallogic.com/contact-us.aspx
Please post any additional questions you may have.
-Joe
brdixon
5 Posts
0
December 20th, 2011 06:00
Hi Joe, Thanks for your reply; I would actually prefer carving up the LUNS, based on RAID group requirements, but from what you have advised (or at least what I understand so far) is that per array, only one RAID group can be configured for this type of storage platform.
Do you have any documentation that is specific for SQL cluster deployments using Single RAID Pool integration? Since all storage will be RAID 10 (configured the way it is now, and most SQL Best Practices call for varying RAID group requirements, etc)?
I tried the number you provided, and after 3 attempts the guy on the other end said he just couldn't hear me... so I tried the 800 sales number from Dell.com, they could hear me just fine, but after 30 minutes and 7 transfers the guy still couldn't help me (or find me in their systems).. albeit we are an Enterprise customer with Dell.
I just need to make sure we configure this thing as best as possible for SQL-only deployments.. if it's single tier RAID across the array/pool, then that's what it is. But if there are some other changes I can make from the OS side of things - including Disk Alignment, Registry Modifications, etc.. then I'd be interested in that info. I haven't had time to read thru all your included documents yet, but I will take the time to go over them.
Thanks JOe
brdixon
5 Posts
0
December 20th, 2011 07:00
Sorry, I misread the first part of your email. So we can indeed split this up into separate Arrays (Groups of RAID Disks). I guess, like I mentioned in my last ill-informed response, I'd like to make sure we are optimizing things for SQL deployments, per Dell testing and development standards. I understand the networking resource concerns, and from what I gather, this has been configured with 2Gbps x 2 (Active Passive) across two 3750 dedicated stack switches. I would assumate that the backplane in these switches can support the logical bandwidth (or Jumbo Frame traffic) that the SAN will be pushing across those ports.
Thanks again for your continued feedback, I appreciate it very much.
--Brian
DELL-Joe S
7 Technologist
7 Technologist
•
729 Posts
0
December 20th, 2011 08:00
Sorry to hear you couldn’t get through to the EqualLogic sales, unfortunately I don’t have any control over that. You may want to just email them and they will call you back:
Sales:
US-NH-sales@dell.com
603-579-9762 x7792
Or if you have a Technical Account Manager (TAM), you could contact them and they should be able to arrange a call for you.
Also, I want to make sure we are on the same page regarding the terminology we use specific to our array;
Group: Can contain more than one member (up to 16 depending on the array models and firmware installed)
Members: Can have only one RAID policy per member and a member can only be in one storage “pool” at a time.
Pool: Can be used to organize your volumes based on user defined reasons, such as; RAID policies, or application needs, etc. However, if you only have one member, you can only have one active pool.
Volumes: Where your data lives. In a single member group, all volumes live on that member (and have the RAID policy of the member). When additional members are added, volumes can be load balanced across additional members that are in the same pool. Also, if you have a pool with two or more members of different RAID types, you can then specify a RAID preference to a volume (provided that one of the members has that RAID policy and the physical space to hold the volume).
So with that said, to address your questions:
Yes, there are several Host side modifications that can be made, including all that you mentioned.
Disk alignment – www.equallogic.com/.../technicaldocumentsview.aspx then go to the “Tech Report” and look for: “Microsoft Windows: Aligning Disk Sectors for Optimal Performance Technical Report” (the reports are listed alphabetically)
Registry modifications – in the firmware release notes (use the RN that is specific for the firmware installed on the array) lists the iSCSI disk timeouts that are needed.
Also on the link above and this link http://media.community.dell.com/en/dtc/attach/tr1013-sql-server_iso.pdf , in the Deploying SQL in a iSCSI SAN document, on Page “v” there are other items to review.
-joe
brdixon
5 Posts
0
December 20th, 2011 08:00
Got it, thanks Joe, I appreciate that. (And as for the Equallogic number, sorry, I thought this was a direct-Dell contact line, I'll try them again another time).
Thanks for your help!
brdixon
5 Posts
0
December 20th, 2011 08:00
I don't know the answer to that, but I will get that information for you Joe.
DELL-Joe S
7 Technologist
7 Technologist
•
729 Posts
0
December 20th, 2011 08:00
Was that the cisco 3750E or 3750G?